I have recently bought a thermos flask so I can have hot tea at work, but on the box it say's it can also keep liquids cold, how does it know what is what.
2007-02-26 06:58:17 · 14 answers · asked by Anonymous in Science & Mathematics ➔ Other - Science
You are a comedian having us on !!
A guy takes his vacuum flask to work and his mate asks him what it's for. He replies that it keeps hot things hot and cold things cold.
His pal says, "What's it it then" ?
The guy replies "Ice cream and hot coffee" !!!
2007-02-26 13:48:22 · answer #1 · answered by Norrie 7 · 1⤊ 0⤋
A thermos flask works by insulation, so it merely keeps liquids at the same temperature that they were when you poured them into the flask. Eventually hot liquids cool and cold liquids warm up as they are not perfect insulators, this is speeded up if you take the lid off frequently and the liquid is warmed or cooled by the air with which it comes into contact.
2007-02-26 07:03:05 · answer #2 · answered by ? 7 · 1⤊ 0⤋
The main bit of the thermos flask is the vacuum. It is mainly the vacuum that stops the transfer of heat energy across the flask boundary - both in and out of the flask.
Hot liquids cool down by transferring heat energy to the surrounding environment. old liquids heat up by absorbing heat energy from its surroundings. For 'liquids' read any mass.
The transfer of heat energy only stops when two masses in contact are both at the same temperature.
2007-02-26 07:12:12 · answer #3 · answered by Bill N 3 · 1⤊ 0⤋
Its just the metal inside which keeps liquid on the temperature it actually has
Tea will be hot so inside of flask will keep hot much as possible
You put cold drink in there it will keep it cold.
This by keeping temperature stable for long time wether its hot or cold
2007-02-26 07:01:54 · answer #4 · answered by Unknown Entity 3 · 1⤊ 0⤋
Because of its insulation. Whatever you put in it whether cold or hot it retains its temperature though not much. If the liquid stay longer it eventually goes cold.
2007-02-26 07:14:28 · answer #5 · answered by briggs 5 · 1⤊ 0⤋
The answer is this The flask does not know
and she does not have to know either.
It goes automaticly how you want it.
She only keeps the temperature constant so cold stays cold, warm stays warm
2007-02-26 07:02:32 · answer #6 · answered by gjmb1960 7 · 1⤊ 0⤋
The flask doesn't know anything.It's just very well insulated so hot things stay warm and cold things stay cool.
2007-02-26 07:01:52 · answer #7 · answered by Gene 7 · 2⤊ 0⤋
LOL, you're joking, right?
The trick is in the insulation. If the contents of the bottle are warmer than the bottle's surroundings, the bottle will keep the heat in. If the contents are colder, the bottle will keep the warmth from the outside to get into the bottle.
2007-02-26 07:02:55 · answer #8 · answered by M 6 · 1⤊ 0⤋
my flask turns hot water into cold within a hour i think its broke.
2007-02-26 07:02:35 · answer #9 · answered by Anonymous · 1⤊ 0⤋
It doesn't it just slows down the rate of change in temperature between contents and outside world
2007-02-26 07:02:43 · answer #10 · answered by Anonymous · 1⤊ 0⤋